The present invention relates generally to transistors, and relates more particularly to the fabrication of heterojunction bipolar transistors.
As heterojunction bipolar transistor (HBT) switching speeds reach over 350 GHz, further improvement in alternating current (AC) performance becomes increasingly dependent on the reduction of base resistance (Rb) (especially in the maximum oscillation frequency, fmax).
Thus, there is a need in the art for a method and apparatus for fabricating a heterojunction bipolar transistor to reduce base resistance in the extrinsic base.